View Full Version : condensed water/steam on glass with pflow?

05 May 2010, 07:27 AM
Hi all,

I've been trying to simulate the sort of steamy droplets you see inside a coffee pot or when you pour hot liquid into a glass. Here's ( an example.

I followed Anselm von Seherr's ( tutorial and managed to get started with droplets on the inside surface of my glass, but it doesn't look too realistic and there's already some 15 000 particles there.

I used birth paint and the paint helper to paint in the particles, but with thousands of particles instancing a hemisphere it starts to get really slow and yet much more would be needed to get it look real with this method.

Any tips? Would it be a better idea to fake this with some sort of bump map or is there a more efficient way creating tens of thousands of tiny little droplets on a surface?

05 May 2010, 07:40 AM
you can apply a mesher modifier to your pflow droplets and apply again a various range of modifiers to achive a better look...surely, a droplets shader is the fastest way (final render have it if I remember)

05 May 2010, 07:44 AM
Thanks for the reply!

I should have mentioned that I only have mental ray, so no special shaders for this, I'm afraid.

I'm currently experimenting if a cellular or speckle map would do the job for the most tiniest droplets...

05 May 2010, 08:16 AM
Not quite there yet,

By combining a cellular bump map and the particles I got this result (obviously the liquid itself is not in the picture) - but it's quite far from the reference.

EDIT: I just tried this in real-life. It seems that when you pour hot water in a cup, the droplets near the surface of the liquid are big and those farther from it (upwards) get smaller and smaller. It's quite even pattern too. Over time the droplets merge and the smaller ones get bigger. Within a minute you have almost equally sized big droplets all over the glass.

So, perhaps a more believable effect could be done by making the particles move along the surface upwards from where the liquid and the glass meet and spawn bigger particles along the way?

05 May 2010, 10:33 AM
in my opinion better way to create droplets is particle flow.
tutorial on evermotio.n is a good piece of start.
you can download a 3dalien pwrapper demo to help much more then blob mesh (my opinion) to achive faster style solutions.

05 May 2010, 10:36 AM

Yes, I'm thinking about that pwrapper. Actually I didn't blobmesh anything yet - those are just "raw" particles in the screenshot - but I don't like the idea of waiting for it to it's job on just one core, once I do need it.

05 May 2010, 12:49 PM
This effect you want to achieve is a difficult one.
And i doubt that you get there only with particle drops.

When you look closely you can recognize a very thin "water film" layer
and the water drops.

Perhaps you can achieve that with a greyscale map in the "Refraction / Reflection" in order
to get the "non glossy" look of that "film" ( condensed film ). That, with the water drop combination will
look much more realistic in my view.



05 May 2010, 01:07 PM
Thanks for the tip,

I tried a cellular map for the smallest drops and it works, surprisingly it works best as a bump map. Perhaps the transparency should also be dimmed down a little on the dense area. Anyways, it is indeed a difficult effect! At least if it should look real.

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05 May 2010, 01:07 PM
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